TEHRAN, Iran - President Mahmoud Ahmadinejad said Iran would free the 15 detained British sailors and marines today as an Easter holiday “gift” to the British people.

He said the captives, who were seized while on patrol in the northern Persian Gulf on March 23, would be taken to the airport following his news conference, but Iranian state television reported they would leave Iran on Thursday. An Iranian official in London said they would be handed over to British diplomats in Tehran.

After the news conference, state television showed Ahmadinejad meeting with the British crew, dressed in business suits, at the presidential palace. He shook hands and chatted with them through a translator, and a caption to the video said the meeting was taking place as part of the “process of release.”

“We appreciate it. Your people have been really kind to us, and we appreciate it very much,” one of the crew could be heard telling Ahmadinejad in English.

Another said: “We are grateful for your forgiveness.”

Ahmadinejad responded in Farsi, “You are welcome.”

Iranian TV said the British captives had watched Ahmadinejad's news conference live and were ecstatic when a translator told them what the president had said.

Their release would end a 13-day standoff between London and Tehran that was sparked when the crew was seized as it searched for smugglers off the Iraqi coast. Britain denied Iranian claims the crew had entered Iranian waters.

In London, the office of Prime Minister Tony Blair said it welcomed the news. President Bush, who had condemned the seizure of the Britons and referred to them as “hostages,” also welcomed the news, said his national security spokesman, Gordon Johndroe.

In New York, British U.N. Ambassador Emyr Jones Parry said “if this news is confirmed, then it's tremendous news and we're delighted.”

Recent days saw talk of direct negotiations between Britain and Iran, and a decrease in tensions that had risen after Iran broadcast videos in which female British sailor Faye Turney and others “confessed” to violating Iranian territorial waters, and Britain expressed outrage.

Ahmadinejad said the British government had sent a letter to the Iranian Foreign Ministry pledging that entering Iranian waters “will not happen again.” Britain issued no immediate confirmation of the letter.

“On the occasion of the birthday of the great prophet (Muhammad) ... and for the occasion of the passing of Christ, I say the Islamic Republic government and the Iranian people - with all powers and legal right to put the soldiers on trial - forgave those 15,” he said, referring to the Muslim prophet's birthday on March 30 and the Easter holiday.

“This pardon is a gift to the British people,” he said.

The surprise announcement came shortly after Ahmadinejad pinned a medal on the chest of the Iranian coast guard commander who intercepted the sailors and marines.

A Downing Street spokeswoman said Blair's office was “establishing exactly what this means in terms of the method and timing of their release.”

An Iranian official in London said the crew members would be handed over to British diplomats in Tehran and that it would then be up to the Foreign Office to decide how they would return home.

“They will go through some brief formalities and then they will go to the embassy,” said the diplomat, who spoke on condition of anonymity because of the sensitivity of the negotiations. “They can go on a British Airways flight to Heathrow, they can go through the UAE (United Arab Emirates), it is up to the British Embassy in Tehran in coordination with the Foreign Office here.”

In London, a Foreign Office spokesman said wanted to “make sure we've actually got them in hand, and that they're safe and well,” before making travel plans.

A group of British service members who were seized by Iran in 2004 were sent back to the British sector of southern Iraq aboard an Iranian commercial flight, after stops in Kuwait and the United Arab Emirates.

Ahmadinejad's announcement came after Iran's state media reported that an Iranian envoy would be allowed to meet five Iranians detained by U.S. forces in northern Iraq. Another Iranian diplomat, separately seized two months ago by uniformed gunmen in Iraq, was released and returned Tuesday to Tehran.

Ahmadinejad said Iran will never accept trespassing in its territorial waters.

“On behalf of the great Iranian people, I want to thank the Iranian coast guard who courageously defended and captured those who violated their territorial waters,” he said.

“We are sorry that British troops remain in Iraq and their sailors are being arrested in Iran,” Ahmadinejad said.

Ahmadinejad asked Blair not to “punish” the crew for confessing that they had been in Iranian waters when they were seized by Iranian coast guard. Iran broadcast video of some of the crew giving confessions, angering Britain.

He also criticized Britain for deploying Turney in the Gulf, pointing out that she is a woman with a child.

“How can you justify seeing a mother away from her home, her children? Why don't they respect family values in the West?” he asked of the British government.

Iran has denied it seized the Britons to force the release of Iranians held in Iraq, and Britain has steadfastly insisted it would not negotiate for the sailors' freedom.

Iran's official Islamic Republic News Agency said earlier today that an Iranian envoy would be allowed to meet with the five detained Iranians in Iraq but gave no further details.